Recently, various cameras have been widely used due to the development of information and communication technology and the increase in the population of Internet users, and thus the demand for image analysis and utilization using the cameras has also been increasing. However, a distortion may occur in an image obtained from a camera due to the characteristics of lens of the camera. Such a distortion may need to be corrected to analyze and utilize the image.
In a case of a wide-angle camera having a wide viewing angle, for example, a camera provided in a vehicle, an image captured by the wide-angle camera may have a severe distortion compared to an image captured by a common type camera. Thus, when representing such an image in an image output device, a distorted image that is compressed horizontally and vertically may be displayed. In addition, it may need to correct a radial distortion that moves inwards or outwards from an original position in response to a further separation from a center of the lens.
Such an image distortion may occur in almost all cameras using lens, and thus many technologies have been developed in various technical fields to correct a distorted image. These technologies have been widely applied to a camera used for a vehicle, in particular, because such a camera is widely used in various fields due to its various functions and purposes.
A representative type of a camera used for a vehicle is a rear-view camera. The rear-view camera may need an external camera and an output device configured to simply output an image captured by the external camera. However, along with the recent development of an advanced driver assistance system (ADAS), there has emerged a need to process an image to be more suitable for the user requirements or a control system, instead of simply outputting the image. It may be needed to process an image of a camera in accordance with a requirement from a user or a system, for example, a requirement for a panoramic view or a top view.
To process an image needed for a vehicle, a distorted image may need to be corrected first. To correct a distortion, the following method may be performed. The method may include defining a camera model, estimating intrinsic and extrinsic parameters of the model from a correction pattern, and then performing restoration through an inverse transformation of the model.
In the estimating of the parameters from the correction pattern, a certain pattern tool may be used for camera calibration. Using such pattern tool, an accurate relative position of a certain marker on a pattern may be verified in advance, and thus an accurate result may be obtained. However, it may cause inconvenience because such a heavy pattern tool may need to be carried around all the time.
An example of related arts includes KR Patent Publication No. 10-2009-0065198 published on Jun. 22, 2009.